Brazing compositions and joining processes of this type are used, for example, in the production and refurbishment of components, in particular components for high-temperature applications. In the case of components for high-temperature applications, such as turbine components in the hot-gas path of a turbine, damage caused by operation can only rarely be prepared using the customary welding and brazing processes, since the strength of the additional materials used is not sufficient for ensuring the structural integrity in the high-temperature environment.
Particular joining and repair processes using a material which cohesively bonds to the parts to be joined or repaired are known from the prior art, for example from EP 1 258 545. In the brazing process described therein, a brazing material having a similar composition to the superalloy of a component is filled into a crack and heated to a temperature above the melting point of the brazing material over a relatively long period of time. Boron is added to the brazing material in order to reduce the melting temperature. Other melting-temperature reducers such as silicon are likewise known from the prior art. The heat treatment involves diffusion processes which reduce the concentration of the melting-point reducer in the brazing material by diffusion such that the brazing material solidifies. In this process, the diffusion leads to a concentration equilibrium with the surrounding superalloy material. The melting-point reducer which diffuses into the superalloy during the heat treatment may lead to brittle precipitates in the superalloy. When boron is used as the melting-point reducer, the precipitation of brittle borides may occur, for example, and these borides impair the mechanical properties of the component in the region of the repaired location.